Liquid material delivering method and device therefor

ABSTRACT

A method and a device for accurate delivery, dripping and ejection in the form of flying droplets are provided.  
     A liquid material delivering method wherein a liquid material is pressurized by a plunger sliding while closely contacting an inner wall surface of a liquid feed passageway establishing communication between a nozzle and a storage section to deliver the liquid material through the nozzle. The plunger is disposed in a space filled with the liquid material. A sliding surface of the plunger section sliding while closely contacting the inner wall surface of the liquid feed passageway divides the space into a nozzle-side liquid material part and a storage container-side liquid material part. Of divided two parts of the liquid material, the liquid material in the nozzle-side liquid material part is delivered by the plunger section advancing in the liquid feed passageway. A liquid material delivering device comprises a liquid material storage section for storing a liquid material, a nozzle section for delivering the liquid material, a liquid feed passageway for establishing communication between the storage section and the nozzle section, a plunger section having a seal portion sliding while closely contacting an inner surface of the liquid feed passageway, and plunger moving means for advancing and retracting the plunger section. The delivering device further comprises another liquid feed passageway  2  for establishing communication between a portion of the aforesaid liquid feed passageway near a nozzle-side distal end thereof and a portion of the aforesaid liquid feed passageway near the liquid material storage section or the liquid material storage section itself, and a liquid feed valve disposed at a distal end of the another liquid feed passageway  2  or midway the another liquid feed passageway  2.

TECHNICAL FIELD

The present invention relates to the field in which a liquid material ispressurized by a plunger sliding while closely contacting an inner wallsurface of a liquid feed passageway to deliver the liquid materialthrough a nozzle. More particularly, the present invention relates to aliquid material delivering method and device, which can preventundesired drying and sticking of the liquid material on the innersurface of the liquid feed passageway and undesired leakage of theliquid material from the plunger, can reduce the volume of a space inwhich the plunger is disposed to pressurize the liquid material, therebyensuring accurate delivery, and can eliminate loss of the liquidmaterial during the operation of purging air bubbles trapped in theliquid material, thereby realizing efficient of the liquid material.

Herein, the term “delivery” means that the liquid material is delivered,dripped, or ejection in the form of flying droplets.

BACKGROUND ART

A known technique for ejecting a liquid material in the form of flyingdroplets employs a retracting and advancing plunger. The plunger isquickly accelerated to advance and then abruptly stopped by abutting itagainst a valve seat. Upon the abrupt stop, an inertial force is appliedto the liquid material present in front of the plunger, thus causing theliquid material to eject in the form of flying droplets under the actionof the inertial force. With such a known technique, however, because theinertial force required for ejecting a liquid material in the form offlying droplets is obtained by abutting a moving solid plunger against astationary solid valve seat and momentarily stopping the movement of theplunger, there arise problems that the plunger and the valve seat areseriously damaged by the abutting. Another problem is that a damagedmember is mixed into the liquid material to melt therein.

With the view of solving those problems, the applicant previouslyproposed a technique wherein, after bringing a distal end surface of aplunger for delivering the liquid material into close contact with theliquid material, the plunger is accelerated to advance at high speed,and subsequently a plunger driving means is abruptly stopped to suddenlystop the plunger advancing at high speed without abutting it against avalve seat, so that an inertial force is applied to the liquid materialpresent in front of the plunger and the liquid material is ejected inthe form of flying droplets by the applied inertial force (JapanesePatent Application No. 2001-319074).

DISCLOSURE OF THE INVENTION

The invention of the above prior application has succeeded in achievingthe intended object, but the following problems were found in theprocess of carrying out the prior invention in practical use.

With repeated operations of advancing and retracting the plunger, theliquid material having seeped little by little through a seal portion ofthe plunger is dried and stuck to an inner wall surface of a meteringsection. As a result, smooth sliding of the plunger is impeded and theliquid material cannot be delivered in a fixed amount. In addition, theliquid material may leak through the seal portion and eventually fail tocome out in some cases.

Also, in the previously proposed device, because the liquid material issupplied from a storage container for storing the liquid material toflow into the metering section via a route in which a liquid materialfeed valve is disposed, the liquid material present between the meteringsection and the liquid material feed valve is also pressurized withadvance of the plunger. In a system requiring a sharp pressure rise,therefore, a factor of preventing the sharp pressure rise is resultedbecause a space uselessly occupied by the liquid material is increased.

Further, in the previously proposed device, because air bubbles arepurged out by discharging trapped gas to open air through a purge holeformed in a plunger rod, the liquid may also be discharged in a mixedstate together with a group of air bubbles. Conventionally, thedischarged liquid material has had to be removed using a piece of rag orthe like.

In the past, therefore, it has been unavoidable that the device iscontaminated with the liquid material adhering to the plunger member andthe liquid is wasted even though in a small amount. In the case of theliquid being expensive, particularly, the waste of the liquid must beavoided even in a small amount. Taking into account influences of airbubbles upon the liquid delivery in a fixed amount, i.e., the fact thatthe liquid including air bubbles trapped therein cannot be delivered ina fixed amount, however, the trapped air bubbles have had to be purgedout in spite of wasting the expensive liquid. Further, when ejecting theliquid material in the form of flying droplets, the presence of airbubbles may disable the satisfactory ejection in some cases.

With the view of solving the problems set forth above, an object of thepresent invention is to provide a method and a device for accuratedelivery, dripping and ejection in the form of flying droplets. Anotherobject of the present invention is to provide a liquid delivering methodand device, which can effectively purge out air bubbled trapped in aliquid material, and can utilize the liquid material, which isdischarged in a mixed state together with a group of air bubbles duringthe air bubble purging operation, again for delivery, dripping andejection in the form of flying droplets without wasting the liquidmaterial.

The present invention resides in a liquid material delivering methodwherein a liquid material is pressurized by a plunger sliding whileclosely contacting an inner wall surface of a liquid feed passagewayestablishing communication between a nozzle and a storage section,thereby delivering the liquid material through the nozzle.

The plunger is disposed in a space filled with the liquid material. Inthis case, the present invention resides in a liquid material deliveringmethod wherein a liquid material is pressurized by a plunger slidingwhile closely contacting an inner wall surface of a liquid feedpassageway establishing communication between a nozzle and a storagesection, the plunger being disposed in a space filled with the liquidmaterial, thereby delivering the liquid material through the nozzle.

A sliding surface of the plunger section sliding while closelycontacting the inner wall surface of the liquid feed passageway dividesthe space into a nozzle-side liquid material part and a storagecontainer-side liquid material part, and of divided two parts of theliquid material, the liquid material in the nozzle-side liquid materialpart is delivered by the plunger section advancing in the liquid feedpassageway. In this case, the present invention resides in a liquidmaterial delivering method wherein a sliding surface of the plungersection, which slides while closely contacting an inner wall surface ofa liquid feed passageway establishing communication between a nozzle anda storage section and which is preferably disposed in a space filledwith the liquid material, divides the space into a nozzle-side liquidmaterial part and a storage container-side liquid material part, and ofdivided two parts of the liquid material, the liquid material in thenozzle-side liquid material part is delivered by the plunger sectionadvancing in the liquid feed passageway.

The plunger section includes a valve mechanism for establishing orcutting off communication between the nozzle-side liquid material partand the storage container-side liquid material part, and the plungersection is advanced in the liquid feed passageway with the valvemechanism held in a closed state, thereby delivering the liquidmaterial. In this case, the present invention resides in a liquidmaterial delivering method wherein a sliding surface of the plungersection, which slides while closely contacting an inner wall surface ofa liquid feed passageway establishing communication between a nozzle anda storage section and which is preferably disposed in a space filledwith the liquid material, divides the space into a nozzle-side liquidmaterial part and a storage container-side liquid material part, theplunger section including a valve mechanism for establishing or cuttingoff communication between the nozzle-side liquid material part and thestorage container-side liquid material part, and of divided two parts ofthe liquid material, the liquid material in the nozzle-side liquidmaterial part is delivered by the plunger section advancing in theliquid feed passageway with the valve mechanism held in a closed state.

A tip of the plunger section is constituted as a plunger head disposedin a flow passage, and the plunger head is advanced in the liquidmaterial, thereby delivering the liquid material. In this case, thepresent invention resides in a liquid material delivering method whereina sliding surface of the plunger section, which slides while closelycontacting an inner wall surface of a liquid feed passagewayestablishing communication between a nozzle and a storage section andwhich is preferably disposed in a space filled with the liquid material,divides the space into a nozzle-side liquid material part and a storagecontainer-side liquid material part, a tip of the plunger section beingconstituted as a plunger head disposed in a flow passage, and of dividedtwo parts of the liquid material, the liquid material in the nozzle-sideliquid material part is delivered by advancing the plunger head of theplunger section in the liquid material.

The delivering method includes a first step of forming the nozzle-sideliquid material part as a closed area, preferably forming the closedarea by using a delivery valve disposed at a distal end of the liquidfeed passageway or midway the liquid feed passageway, and morepreferably forming the closed area by using closing means for closing adelivery port at a nozzle tip, a second step of retracting the plungersection to feed the liquid into the liquid feed passageway from theliquid material storage section, and a third step of advancing theplunger section to deliver the liquid material. In this case, thepresent invention resides in a liquid material delivering method whereina sliding surface of the plunger section, which slides while closelycontacting an inner wall surface of a liquid feed passagewayestablishing communication between a nozzle and a storage section andwhich is preferably disposed in a space filled with the liquid material,divides the space into a nozzle-side liquid material part and a storagecontainer-side liquid material part, and of divided two parts of theliquid material, the liquid material in the nozzle-side liquid materialpart is delivered by the plunger section advancing in the liquid feedpassageway, the delivering method including a first step of forming thenozzle-side liquid material part as a closed area, preferably formingthe closed area by using a delivery valve disposed at a distal end ofthe liquid feed passageway or midway the liquid feed passageway, andmore preferably forming the closed area by using closing means forclosing a delivery port at a nozzle tip, a second step of retracting theplunger section to feed the liquid into the liquid feed passageway fromthe liquid material storage section, and a third step of advancing theplunger section to deliver the liquid material.

The first step includes a fifth step of establishing communicationbetween the nozzle-side liquid material part and the storagesection-side liquid material part. The fifth step is preferablyperformed with the valve mechanism provided in the plunger section. Thedelivering method includes, between the second step and the third step,a fourth step of purging out air bubbles trapped in the liquid materialin the liquid feed passageway as the occasion requires. In this case,the present invention resides in a liquid material delivering methodwherein a sliding surface of the plunger section, which slides whileclosely contacting an inner wall surface of a liquid feed passagewayestablishing communication between a nozzle and a storage section andwhich is preferably disposed in a space filled with the liquid material,divides the space into a nozzle-side liquid material part and a storagecontainer-side liquid material part, and of divided two parts of theliquid material, the liquid material in the nozzle-side liquid materialpart is delivered by the plunger section advancing in the liquid feedpassageway, the delivering method including a first step of forming thenozzle-side liquid material part as a closed area, preferably formingthe closed area by using a delivery valve disposed at a distal end ofthe liquid feed passageway or midway the liquid feed passageway, andmore preferably forming the closed area by using closing means forclosing a delivery port at a nozzle tip, the first step including afifth step of establishing communication between the nozzle-side liquidmaterial part and the storage section-side liquid material part, thefifth step being preferably performed with the valve mechanism providedin the plunger section, a second step of retracting the plunger sectionto feed the liquid into the liquid feed passageway from the liquidmaterial storage section, and a third step of advancing the plungersection to deliver the liquid material, the delivering method furtherincluding, between the second step and the third step, a fourth step ofpurging out air bubbles trapped in the liquid material in the liquidfeed passageway as the occasion requires.

The fourth step comprises a sixth step of forming the nozzle-side liquidmaterial part as a closed area and establishing communication betweenthe nozzle-side liquid material part and the storage section-side liquidmaterial part, and a seventh step of advancing the plunger section. Inthis case, the present invention resides in a liquid material deliveringmethod wherein a sliding surface of the plunger section, which slideswhile closely contacting an inner wall surface of a liquid feedpassageway establishing communication between a nozzle and a storagesection and which is preferably disposed in a space filled with theliquid material, divides the space into a nozzle-side liquid materialpart and a storage container-side liquid material part, and of dividedtwo parts of the liquid material, the liquid material in the nozzle-sideliquid material part is delivered by the plunger section advancing inthe liquid feed passageway, the delivering method including a first stepof establishing the nozzle-side liquid material part as a closed area,preferably forming the closed area by using a delivery valve disposed ata distal end of the liquid feed passageway or midway the liquid feedpassageway, and more preferably forming the closed area by using closingmeans for closing a delivery port at a nozzle tip, the first stepincluding a fifth step of establishing communication between thenozzle-side liquid material part and the storage section-side liquidmaterial part, the fifth step being preferably performed with the valvemechanism provided in the plunger section, a second step of retractingthe plunger section to feed the liquid into the liquid feed passagewayfrom the liquid material storage section, and a third step of advancingthe plunger section to deliver the liquid material, the deliveringmethod further including, between the second step and the third step, afourth step of purging out air bubbles trapped in the liquid material inthe liquid feed passageway as the occasion requires, the fourth stepcomprising a sixth step of forming the nozzle-side liquid material partas a closed area and establishing communication between the nozzle-sideliquid material part and the storage section-side liquid material part,and a seventh step of advancing the plunger section.

Also, the present invention resides in a liquid material deliveringdevice comprising a liquid material storage section for storing a liquidmaterial, a nozzle section for delivering the liquid material, a liquidfeed passageway for establishing communication between the storagesection and the nozzle section, a plunger section having a seal portionsliding while closely contacting an inner surface of the liquid feedpassageway, and plunger moving means for advancing and retracting theplunger section, the delivering device further comprising another liquidfeed passageway 2 for establishing communication between a portion ofthe liquid feed passageway near a nozzle-side distal end thereof and aportion of the liquid feed passageway near the liquid material storagesection or the liquid material storage section itself, and a liquid feedvalve disposed at a distal end of the another liquid feed passageway 2or midway the anther liquid feed passageway 2.

Further, the present invention resides in a liquid material deliveringdevice comprising a liquid material storage section for storing a liquidmaterial, a nozzle section for delivering the liquid material, a liquidfeed passageway for establishing communication between the storagesection and the nozzle section, a plunger section having a seal portionsliding while closely contacting an inner surface of the liquid feedpassageway, plunger moving means for advancing and retracting theplunger section, a delivery valve disposed at a nozzle-side distal endof the liquid feed passageway or midway the liquid feed passageway, andanother liquid feed passageway 2 for establishing communication betweenthe delivery valve and a portion of the liquid feed passageway near theliquid material storage section or the liquid material storage sectionitself, the delivery valve taking a first position at which the liquidfeed passageway is communicated with the nozzle, and a second positionat which the liquid feed passageway is communicated with the anotherliquid feed passageway 2.

Still further, the present invention resides in a liquid materialdelivering device comprising a liquid material storage section forstoring a liquid material, a nozzle section for delivering the liquidmaterial, a liquid feed passageway for establishing communicationbetween the storage section and the nozzle section, and a plungersection having a seal portion sliding while closely contacting an innersurface of the liquid feed passageway, the plunger section including avalve mechanism for establishing or cutting off communication betweenthe nozzle section and the storage section. Preferably, the deliveringdevice further comprises a delivery valve disposed in a portion of theliquid feed passageway neat a nozzle-side distal end thereof or midwaythe liquid feed passageway. As appropriate, the inner diameter of theliquid feed passageway and the inner diameter of the delivery valve aresubstantially equal to each other.

In the liquid material delivering device of the present invention, morespecifically, the plunger section comprises a plunger rod having atubular portion formed with a first hole 1 opened to an outer wallsurface of the plunger rod, a plunger head fitted to a tip of theplunger rod, having a second hole 2 communicating with the tubularportion of the plunger rod, and including a seal portion projecting onan outer wall surface of the plunger head to be closely contacted withthe inner wall surface of the liquid feed passageway, a valve rodinserted in the tubular portion of the plunger rod, valve rod drivingmeans for moving the valve head to be closely contacted with or apartaway from the plunger head, a valve rod, and valve driving means foradvancing and retracting the valve rod.

In that case, the liquid material delivering device delivers the liquidmaterial through a first step of closing the delivery valve and openingthe valve rod inserted in the tubular portion of the plunger rod withrespect to the plunger head, a second step of retracting the plungersection to feed the liquid material into the liquid feed passageway fromthe liquid material storage section, a second step of retracting theplunger section to move the liquid material from the storagesection-side liquid material part into the nozzle-side liquid materialpart, a third step of opening the delivery valve and closing the valverod, and a fourth step of advancing and the plunger section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view showing one embodiment of the presentinvention in which; FIG. 1(a) is a front view and FIG. 1(b) is a sideview.

FIG. 2 is a conceptual view showing another embodiment of the presentinvention in which; FIG. 2(a) is a front view and FIG. 2(b) is a sideview.

FIG. 3 is a conceptual view showing still another embodiment of thepresent invention in which; FIG. 3(a) is a front view and FIG. 3(b) is aside view.

FIG. 4 is a side view of a principal part of the embodiment shown inFIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

A sliding surface of a plunger section sliding while closely contactingan inner wall surface of a liquid feed passageway for establishingcommunication between a nozzle and a liquid material storage sectiondivides a liquid material space into a nozzle-side liquid material partand a storage container-side liquid material part, and of divided twoparts of the liquid material, the liquid material in the nozzle-sideliquid material part is delivered by the plunger section advancing inthe liquid feed passageway. Here, the amount of the delivered liquidmaterial is decided depending on the amount by which the plunger sectionis advanced. Also, since the sliding surface of the plunger section isdisposed in a flow passage defined by the liquid feed passageway, a tipof the plunger section is always kept in contact with the liquidmaterial.

Preferably, the plunger section includes a valve mechanism forestablishing or cutting off communication between the nozzle-side liquidmaterial part and the storage container-side liquid material part, andthe plunger section is advanced in the liquid feed passageway with thevalve mechanism held in a closed state, thereby delivering the liquidmaterial.

Because of the plunger section including the valve mechanism, it is nolonger required to branch the flow passage for feeding the liquidmaterial.

During the delivery, in particular, since the plunger section isadvanced with the valve mechanism held in the closed state, the liquidmaterial can be smoothly pressurized for the delivery.

Also, preferably, a tip of the plunger section is constituted as aplunger head disposed in the flow passage, and the plunger head isadvanced in the liquid material.

The plunger head constituted by the tip of the plunger section directlypressurizes the liquid material to be delivered. Since the plunger isdisposed in the flow passage, the plunger head is always positioned inthe liquid material and an outer peripheral of the plunger head is heldin contact with the liquid material.

In the liquid material delivering method wherein the plunger section isadvanced while closely contacting the inner wall surface of the liquidfeed passageway to deliver the liquid material, the delivering processincludes a first step of forming the nozzle-side liquid material part asa closed area by using closing means, a second step of retracting theplunger section to feed the liquid into the liquid feed passageway fromthe liquid material storage section, and a third step of advancing theplunger section to deliver the liquid material.

Preferably, the first step includes a fifth step of establishingcommunication between the nozzle-side liquid material part and thestorage section-side liquid material part.

More preferably, the delivering method includes, between the second stepand the third step, a fourth step of purging out air bubbles trapped inthe liquid material in the liquid feed passageway. Even more preferably,the fourth step comprises a sixth step of forming the nozzle-side liquidmaterial part as a closed area by using the closing means andestablishing communication between the nozzle-side liquid material partand the storage section-side liquid material part, and a seventh step ofadvancing the plunger section.

The closing means is preferably a delivery valve disposed at a distalend of the liquid feed passageway or midway the liquid feed passageway.The nozzle-side liquid material part can be formed as the closed area bysetting the delivery valve to its closed position. As an alternative,the closing means closes a delivery port at a nozzle tip. In practice, acap or a similar means may be fitted to the delivery port for closingit.

Preferably, the fifth step is performed with the valve mechanismprovided in the plunger section.

When using the valve mechanism provided in the plunger section, theliquid material is preferably delivered through a 21st step of closingthe delivery valve and opening the valve rod (i.e., 21st step of formingthe nozzle-side liquid material part as the closed area and opening theplunger valve mechanism), a 22nd step of retracting the plunger sectionto feed the liquid material into the measuring section from the liquidmaterial storage section, a 23rd step of retracting the plunger sectionto move the liquid material from the storage section-side liquidmaterial part into the nozzle-side liquid material part, a 24th step ofopening the delivery valve and closing the valve rod, and a 25th step ofadvancing and the plunger section.

A liquid material delivering device comprises a liquid material storagesection for storing a liquid material, a nozzle section for deliveringthe liquid material, a liquid feed passageway for establishingcommunication between the storage section and the nozzle section, aplunger section having a seal portion sliding while closely contactingan inner surface of the liquid feed passageway, and plunger moving meansfor advancing and retracting the plunger section, the delivering devicefurther comprising another liquid feed passageway 2 for establishingcommunication between a portion of the liquid feed passageway near anozzle-side distal end thereof and a portion of the liquid feedpassageway near the liquid material storage section or the liquidmaterial storage section itself, and a liquid feed valve disposed at adistal end of the another liquid feed passageway 2 or midway the antherliquid feed passageway 2.

Unlike the prior art in which only the pressurizing surface of theplunger contacts the liquid material, the plunger section is disposed inthe flow passage of the liquid material to be always immersed in theliquid material, and the inner wall surface of the liquid feedpassageway, along which the plunger slides, is always kept in contactwith the liquid material. Therefore, the liquid material is avoided fromdrying and sticking to the plunger surface and the inner wall surface ofthe liquid feed passageway. Also, from the viewpoint of the devicestructure, there is no possibility in principle that the liquid materialmay undesirably leak from the plunger and may stick to the componentsand positions, which should be essentially kept from sticking of theliquid material.

The liquid feed passageway is provided between the liquid materialstorage section for storing the liquid material and the nozzle fordelivering the liquid material, and the liquid material is pressurizedby the plunger sliding while closely contacting the inner wall surfaceof the liquid feed passageway to deliver the liquid material through thenozzle.

To feed the liquid material from the liquid material storage sectioninto the liquid feed passageway, the nozzle-side liquid material part inwhich one of two parts of the liquid material, divided by the plunger,nearer to the nozzle is positioned must be brought into a closed state.

The delivery valve is required to close the nozzle-side liquid materialpart. As an alternative, the nozzle-side liquid material part may beclosed by fitting a cap to a nozzle tip instead of using the deliveryvalve.

The delivering device of the present invention comprises a liquidmaterial storage section for storing a liquid material, a nozzle sectionfor delivering the liquid material, a liquid feed passageway forestablishing communication between the storage section and the nozzlesection, a plunger section having a seal portion sliding while closelycontacting an inner surface of the liquid feed passageway, and plungermoving means for advancing and retracting the plunger section, thedelivering device further comprising another liquid feed passageway 2for establishing communication between a portion of the liquid feedpassageway near a nozzle-side distal end thereof and a portion of theliquid feed passageway near the liquid material storage section or theliquid material storage section itself, and a liquid feed valve disposedat a distal end of the another liquid feed passageway 2 or midway theanther liquid feed passageway 2. Two parts of the liquid materialdivided by the sliding surface of the plunger section sliding whileclosely contacting the inner surface of the liquid feed passageway arecommunicated with each other through the delivery valve so that theliquid material can be fed to the liquid feed passageway 1.

Operation

The liquid material delivering device of the present invention comprisesa liquid material storage section for storing a liquid material, anozzle section for delivering the liquid material, a liquid feedpassageway for establishing communication between the storage sectionand the nozzle section, a plunger section having a seal portion slidingwhile closely contacting an inner surface of the liquid feed passageway,and plunger moving means for advancing and retracting the plungersection, the delivering device further comprising another liquid feedpassageway 2 for establishing communication between a portion of theliquid feed passageway near a nozzle-side distal end thereof and aportion of the liquid feed passageway near the liquid material storagesection or the liquid material storage section itself, and a liquid feedvalve disposed at a distal end of the another liquid feed passageway 2or midway the anther liquid feed passageway 2.

Unlike the prior art in which only the pressurizing surface of theplunger contacts the liquid material, the plunger section is disposed inthe flow passage of the liquid material to be always immersed in theliquid material, and the inner wall surface of the liquid feedpassageway, along which the plunger slides, is always kept in contactwith the liquid material. Therefore, the liquid material is avoided fromdrying and sticking to the plunger surface and the inner wall surface ofthe liquid feed passageway. Also, from the viewpoint of the devicestructure, there is no possibility in principle that the liquid materialmay undesirably leak from the plunger and may stick to the componentsand positions, which should be essentially kept from sticking of theliquid material.

According to the present invention, the liquid feed passageway isprovided between the liquid material storage section for storing theliquid material and the nozzle for delivering the liquid material, andthe liquid material is pressurized by the plunger sliding while closelycontacting the inner wall surface of the liquid feed passageway todeliver the liquid material through the nozzle.

To feed the liquid material from the liquid material storage sectioninto the liquid feed passageway, the nozzle-side liquid material part inwhich one of two parts of the liquid material, divided by the plunger,nearer to the nozzle is positioned must be closed.

The delivery valve is required to close the nozzle-side liquid materialpart. As an alternative, the nozzle-side liquid material part may beclosed by fitting a cap to a nozzle tip instead of using the deliveryvalve.

By quickly accelerating the plunger to advance and then abruptlystopping the plunger so as to apply a great inertial force to the liquidmaterial, the liquid material in the nozzle-side liquid material part isejected to fly in the form of small droplets while the amount of theejected liquid droplets is controlled depending on, e.g., the movingspeed of the plunger and the distance of movement of the plunger.

Also, by operating the plunger to be quickly accelerated to advance andthen abruptly stopped, the liquid material filled in the nozzle-sideliquid material part is given with an inertial force, whereby the liquiddroplets are delivered through the nozzle tip. The delivering operationis carried out by delivering the liquid material, which has been dividedand moved into the nozzle-side liquid material part each time when theplunger is advanced, through the steps of quickly accelerating theplunger to advance and then abruptly stopping it, which are repeatedplural times.

Alternatively, the liquid material, which has been divided and movedinto the nozzle-side liquid material part each time when the plunger isadvanced, can also be ejected in the form of flying droplets at a timewith proper adjustment of the moving speed of the plunger and thedistance of movement of the plunger.

In order to eject the liquid material in the form of flying droplets,therefore, an acceleration, i.e., a speed difference, applied to theplunger is important. The plunger must be moved at high speed by initialacceleration and then abruptly stopped. The plunger is controlled by theplunger driving means in such a manner. Increasing the plunger speed upto a level necessary for ejecting the liquid material in the form offlying droplets requires a distance for acceleration through which theplunger is accelerated to a certain level.

Note that the amount of the ejected liquid droplets is dependent on thedistance of movement of the plunger, but if the distance of movement ofthe plunger is set to be short depending on the amount of the ejectedliquid droplets, the plunger speed required for ejecting the liquidmaterial in the form of flying droplets cannot be obtained. Based on therelationship between the amount of the ejected liquid droplets and themoving speed of the plunger suitable for ejecting the liquid material inthe form of flying droplets, therefore, specifications of the liquidfeed passageway and the plunger are decided so that the distance ofmovement of the plunger sufficient to provide the required plunger speedis obtained.

Further, to reduce the amount of the ejected liquid droplets, it isneeded to shorten the stroke (distance of movement) of the plunger. Onthe other hand, the stroke (distance of movement) of the plunger must beincreased from the viewpoint of obtaining the plunger speed sufficientto eject the liquid material in the form of flying droplets. In order tosatisfy those contradictory demands at the same time, the liquid feedpassageway is designed to be relatively thin so that the distance ofmovement of the plunger is ensured which provides the plunger speedsufficient to eject the liquid material in the form of flying droplets.Also, with the thinning of the liquid feed passageway, the volumeproduced by the movement of the plunger, i.e., the amount of the ejectedliquid droplets, can be reduced even when the plunger is moved over arelatively large stroke.

Several embodiments of the present invention will be described belowwith reference to the drawings, but the present invention is limited inno way by the following embodiments.

In the following description of Embodiments 1 to 3, the same componentsare denoted by the same reference numerals.

EMBODIMENT 1

One embodiment of the present invention comprises, as shown in FIG. 1, aliquid material storage section 1 for storing a liquid material, anozzle section 3 for delivering the liquid material, a liquid feedpassageway 2 for establishing communication between the storage sectionand the nozzle section 3, a plunger section 4 having a seal portionsliding while closely contacting an inner surface of the liquid feedpassageway 2, a plunger moving means 5 for advancing and retracting theplunger section 4, a liquid feed passageway 6 for establishingcommunication between the liquid material storage section 1 and aportion of the liquid feed passageway 2 near a nozzle-side distal endthereof, a liquid feed valve 7 disposed midway the liquid feedpassageway 6, and a frame 9 for supporting the above-mentionedcomponents.

The frame 9 comprises a guide rod for guiding a plunger support in thevertical direction, an upper frame for supporting a screw shaft to movethe plunger support in the vertical direction, and a support frame forsupporting a storage container constituting the liquid material storagesection 1.

The liquid material storage section 1 is a container made up of acylindrical main body opened upward and a bowl-like bottom portion. Aport for connection to the liquid feed passageway is opened in thebottom portion, and the liquid feed passageway 2 is connected to theport in coaxial relation to the container. Accordingly, the storagecontainer surrounds the liquid feed passageway 2 such that a part of theplunger section 4 is always immersed in the liquid material stored inthe container of the storage section 1 during the operation.

The liquid feed passageway 2 has a cylindrical shape with a nozzlefitted to its lower end. The nozzle and the plunger having the sealportion closely contacting the inner peripheral surface of the liquidfeed passageway 2 cooperatively constitute a pump.

Further, the liquid material storage section 1 and the liquid feedpassageway 2 are connected to each other through the liquid feed valve 7disposed between them, and the liquid material in the liquid materialstorage section 1 is supplied to the liquid feed passageway 2 throughthe liquid feed valve 7. The liquid material supplied to the liquid feedpassageway 2 is given with an inertial force from the plunger, which isquickly accelerated to advance and then abruptly stopped, so that theliquid material is delivered in the form of droplets through the nozzle.

FIG. 2 shows another embodiment of the present invention. A liquidmaterial delivering device of this embodiment comprises a liquidmaterial storage section 1 for storing a liquid material, a nozzlesection 3 for delivering the liquid material, a liquid feed passageway 2for establishing communication between the storage section and thenozzle section 3, a plunger section 4 having a seal portion slidingwhile closely contacting an inner surface of the liquid feed passageway2, a plunger moving means 5 for advancing and retracting the plungersection 4, a delivery valve 8 disposed at a nozzle-side distal end ofthe liquid feed passageway 2 or midway the liquid feed passageway 2, aliquid feed passageway 6 for establishing communication between thedelivery valve 8 and a portion of the liquid feed passageway 2 near theliquid material storage section 1 or the liquid material storage section1 itself, and a frame 9 for supporting the above-mentioned components.The delivery valve 8 can take a first position at which the liquid feedpassageway 2 is communicated with the nozzle, and a second position atwhich the liquid feed passageway 2 is communicated with the liquid feedpassageway 6.

FIG. 3 shows still another embodiment of the present invention. A liquidmaterial delivering device of this embodiment comprises a liquidmaterial storage section 1 for storing a liquid material, a nozzlesection 3 for delivering the liquid material, a liquid feed passageway 2for establishing communication between the storage section and thenozzle section 3, a plunger section 4 having a seal portion slidingwhile closely contacting an inner surface of the liquid feed passageway2, a plunger moving means 5 for advancing and retracting the plungersection 4, and a frame 9 for supporting the above-mentioned components.The plunger section 4 includes a valve mechanism for establishing orcutting off communication between the nozzle section 3 and the storagesection, and a delivery valve 8 disposed near a nozzle-side distal endof the liquid feed passageway 2 and having a flow passage having thesame inner diameter as that of the liquid feed passageway 2.

Further, the plunger section 4 in this embodiment includes an air bubblepurging mechanism shown in FIG. 4.

More specifically, the plunger section 4 includes an air bubble purgingmechanism comprising a plunger rod 11 having a tubular portion formedwith an air bubble purging hole 13 opened to an outer wall surface ofthe plunger rod, a plunger head 12 fitted to a tip of the plunger rod11, having an air bubble purging hole 14 communicating with the tubularportion of the plunger rod 11, and including a seal portion 13projecting on an outer wall surface of the plunger head to be closelycontacted with the inner wall surface of the liquid feed passageway 2, avalve rod 16 inserted in the tubular portion of the plunger rod 11, andan air cylinder 17 serving as a valve rod driving means for moving thevalve rod 16 to open or close the air bubble purging hole 14 of theplunger head 12. When the air cylinder 17 is operated to retract thevalve rod 16, the valve rod 16 is moved in the lengthwise direction ofthe plunger rod 11, thus causing a tip of the valve rod 16 to move awayfrom the plunger head 12. Accordingly, the air bubble purging hole 14formed in the plunger head 12 is opened and communicated with theexterior via the air bubble purging hole 14 and a gap formed between theplunger rod 11 and the valve rod 16. In this state, the plunger section4 is advanced to purge air bubbles forwardly of the plunger head 12 tothe exterior.

The above-described air bubble purging mechanism is also applicable toEmbodiments 1 and 2. Also, the valve rod may be moved by using a screwas disclosed in the above-cited prior application.

Industrial Applicability

Thus, according to the present invention, since the sliding surface ofthe plunger and the inner surface of the liquid feed passageway, alongwhich the plunger slides, are always kept in contact with the liquidmaterial, the sliding surface of the plunger and the inner surface ofthe liquid feed passageway, along which the plunger slides, are avoidedfrom drying and sticking to each other. It is therefore possible toeffectively prevent undesired sliding resistance against the movement ofthe plunger from increasing due to those phenomena, and to accuratelysupply the liquid material by delivery, dripping, or ejection in theform of flying droplets.

Also, since the delivering device can be arranged such that the liquidfeed passageway subjected to pressurization is not always required tohave a branched pipe for feeding the liquid material, a necessarysmallest amount of the liquid material can be efficiently pressurized.It is therefore possible to accurately supply the liquid material bydelivery, dripping, or ejection in the form of flying droplets.

With the operation of purging out air bubbles trapped in the liquidmaterial, the liquid material discharged in a mixed state together witha group of air bubbles can be reused while effectively purging out theair bubbles. It is therefore possible to effectively utilize the liquidmaterial, which is discharged during the air bubble purging operation,again for delivery, dripping, or ejection in the form of flying dropletswithout wasting the liquid material.

1. A liquid material delivering method wherein a liquid material is pressurized by a plunger sliding while closely contacting an inner wall surface of a liquid feed passageway establishing communication between a nozzle and a storage section, thereby delivering the liquid material through said nozzle.
 2. A liquid material delivering method according to claim 1, wherein said plunger is disposed in a space filled with the liquid material.
 3. A liquid material delivering method according to claim 1, wherein a sliding surface of said plunger section sliding while closely contacting the inner wall surface of said liquid feed passageway divides said space into a nozzle-side liquid material part and a storage container-side liquid material part, and of divided two parts of he liquid material, the liquid material in the nozzle-side liquid material part is delivered by said plunger section advancing in said liquid feed passageway.
 4. A liquid material delivering method according to claim 3, wherein said plunger section includes a valve mechanism for establishing or cutting off communication between the nozzle-side liquid material part and the storage container-side liquid material part, and said plunger section is advanced in said liquid feed passageway with said valve mechanism held in a closed state, thereby delivering the liquid material.
 5. A liquid material delivering method according to claim 3, wherein a tip of said plunger section is constituted as a plunger head disposed in a flow passage, and said plunger head is advanced in the liquid material, thereby delivering the liquid material.
 6. A liquid material delivering method according to claim 3, wherein the delivering method includes a first step of forming the nozzle-side liquid material part as a closed area, a second step of retracting said plunger section to feed the liquid into said liquid feed passageway from said liquid material storage section, and a third step of advancing said plunger section to deliver the liquid material.
 7. A liquid material delivering method according to claim 6, wherein said first step includes a fifth step establishing communication between the nozzle-side liquid material part and the storage section-side liquid material part.
 8. A liquid material delivering method according to claim 6, wherein the delivering method includes, between said second step and said third step, a fourth step of purging out air bubbles trapped in the liquid material in said liquid feed passageway.
 9. A liquid material delivering method according to claim 8, wherein said fourth step comprises a sixth step of forming the nozzle-side liquid material part as a closed area and establishing communication between the nozzle-side liquid material part and the storage section-side liquid material part, and a seventh step of advancing said plunger section.
 10. A liquid material delivering method according to any one of claim 6, wherein a delivery valve disposed at a distal end of said liquid feed passageway or midway said liquid feed passageway is used as means for closing the nozzle-side liquid material part.
 11. A liquid material delivering method according to claim 10, wherein said closing means closes a delivery port at a nozzle tip.
 12. A liquid material delivering method according to claim 7, wherein said fifth step is performed with said valve mechanism provided in said plunger section.
 13. A liquid material delivering device comprising: a liquid material storage section for storing a liquid material, a nozzle section for delivering the liquid material, a liquid feed passageway for establishing communication between said storage section and said nozzle section, a plunger section having a seal portion sliding while closely contacting an inner surface of the liquid feed passageway, and plunger moving means for advancing and retracting said plunger section, the delivering device further comprising another liquid feed passageway 2 for establishing communication between a portion of said liquid feed passageway near a nozzle-side distal end thereof and a portion of said liquid feed passageway near said storage section or said storage section itself, and a liquid feed valve disposed at a distal end of said another liquid feed passageway 2 or midway said anther liquid feed passageway
 2. 14. A liquid material delivering device comprising: a liquid material storage section for storing a liquid material, a nozzle section for delivering the liquid material, a liquid feed passageway for establishing communication between said storage section and said nozzle section, a plunger section having a seal portion sliding while closely contacting an inner surface of the liquid feed passageway, plunger moving means for advancing and retracting said plunger section, a delivery valve disposed at a nozzle-side distal end of said liquid feed passageway or midway said liquid feed passageway, and another liquid feed passageway 2 for establishing communication between said delivery valve and a portion of said liquid feed passageway near said liquid material storage section or said liquid material storage section itself, said delivery valve taking a first position at which said liquid feed passageway is communicated with said nozzle, and a second position at which said liquid feed passageway is communicated with said another liquid feed passageway
 2. 15. A liquid material delivering device comprising: a liquid material storage section for storing a liquid material, a nozzle section for delivering the liquid material, a liquid feed passageway for establishing communication between said storage section and said nozzle section, and a plunger section having a seal portion sliding while closely contacting an inner surface of the liquid feed passageway, said plunger section including a valve mechanism for establishing or cutting off communication between said nozzle section and said storage section.
 16. A liquid material delivering device according to claim 15, further comprising a delivery valve disposed in a portion of said liquid feed passageway neat a nozzle-side distal end thereof or midway said liquid feed passageway.
 17. A liquid material delivering device according to claim 15, wherein the inner diameter of said liquid feed passageway and the inner diameter of said delivery valve are substantially equal to each other.
 18. A liquid material delivering device according to claim 15, wherein said plunger section comprises a plunger rod having a tubular portion formed with a first hole 1 opened to an outer wall surface of said plunger rod, a plunger head fitted to a tip of said plunger rod, having a second hole 2 communicating with the tubular portion of said plunger rod, and including a seal portion projecting on an outer wall surface of said plunger head to be closely contacted with the inner wall surface of said liquid feed passageway, a valve rod inserted in the tubular portion of said plunger rod, valve rod driving means for moving said valve rod to be closely contacted with or apart away from the plunger head, a valve rod, and valve driving means for advancing and retracting said valve rod.
 19. A liquid material delivering device according to claim 18, wherein the delivering device delivers the liquid material through the steps of: a first step of closing said delivery valve and opening said valve rod inserted in the tubular portion of said plunger rod with respect to said plunger head, a second step of retracting said plunger section to feed the liquid material into said liquid feed passageway from said liquid material storage section, a second step of retracting said plunger section to move the liquid material from the storage section-side liquid material part into the nozzle-side liquid material part, a third step of opening said delivery valve and closing said valve rod, and a fourth step of advancing and said plunger section. 